metaruss » Electron Tube Audio

Simple SE – Fire in the Bottles

Russ — Tue, 05 May 2009 22:15:42 +0000

It’s finally done.

Tubelab Simple SE Breadboard

Russ — Sun, 22 Mar 2009 15:15:24 +0000

With the right iron, the Tubelab Simple SE comes to life. After a sanity-check with cheap Chinese tubes, here is the amp running with JJ 6L6GCs strapped as triodes. The amp sounds sweet with a bit more power than the Tubelab SE.

This coincides with the new speakers that I recently got off of Craigslist: a pair of Klipsch KLF-10s. The horns on these do cause ear fatigue on the Dynaco, but with this amp it is more subdued. I am hoping that the DHTs in the Tubelab SE will be even better.

The basement in currently under construction, so the setup is a bit MacGyver.

Tubelab SE Breadboard

Russ — Mon, 16 Mar 2009 14:56:59 +0000

So I’ve finally built-up this Tubelab SE, a small, single-ended, 2 watt amp. It’s currently in breadboard form, but it sounds amazing. Awesome detail, impressive bass, and something warm about the sound.

Tube Fluorescence

Russ — Wed, 04 Feb 2009 06:46:26 +0000

These are the output tubes on my Thomas amp. You can see the blue glow against the glass from stray electrons. This is very common with Sylvania tubes. Behind the blue glow, is the red glowing line from the electron beam hitting the plates (I can’t get the bias to go any lower with this amp). The two together look purple to the camera.

I have read contradictory discussions about blue glow against the glass envelope. Blue glow coming from inside or near the anode or other structures is normal, but some say that blue glow outside of that means a soft vacuum. Sylvania claims the opposite and that fluorescent glow inside the envelope is normal for some tubes. It results from stray electrons bombarding near the glass envelope and will change in brightness depending on the intensity of the signal passing through the tube. This is exactly what I see with these Philips JAN tubes, which are basically Sylvania. In fact when I push the amp really hard well into cut-off, the tubes will flash brightly signaling me to back-off

The “Winged-C” SED EL34s in the Dynakit seem to fluoresce at the screen behind the plate:

Made in Chian

Russ — Thu, 29 Jan 2009 07:53:13 +0000

All the best stuff comes from Chian.

Why Tubes?

Russ — Sat, 01 Feb 2003 09:29:35 +0000

Why thermionic electron emission devices (valves to our friends in the UK)? Well, I grew up listening to my LPs, cassettes, and the radio through a 6V6GT push-pull instrument amplifier and eventually found that I really missed its sound. I actually didn’t know what it was I didn’t like about my audio system until I fired up that old amp again. The brash, gritty sound was gone. See my Thomas 6V6GT PP amp for more about that. I don’t consider myself to be an audiophile, however the difference to me is noticeable. For an excellent article with a bit of empirical evidence, take a look at Tubes Vs. Transistors by Russell O. Hamm.

The other part of the answer to this question is that I enjoy the challenge as much as (if not more than) the results of my efforts. In terms of components in the signal path, electron tube amplifiers are about as simple as it can get. Perhaps some of the healthy fear involved in working with lethal voltages has something to do with it as well. Finally, tubes are just damn cool. They operate on such a macro scale that you can actually “see” the process take place inside them that is providing you with service that you took the time to design/modify. They’re also pretty to look at….